Syringe-to-syringe mixing systems and related apparatus and methods

ABSTRACT

A hollow syringe barrel for use in syringe mixing systems for mixing a two-component composition. A hollow body of the syringe barrel includes a proximal end, a distal end, and continuous cylindrical wall defining an internal chamber for containing a first component. A rupturable membrane disposed at the distal end caps and seals off a single dispensing orifice. A second syringe barrel can be coupled to the distal end of the hollow syringe barrel to form a syringe-to-syringe mixing system. First and second plungers disposed within the hollow syringe barrel and second syringe barrel, respectively, are used to mix and cycle back and forth first and second components initially contained within the hollow syringe barrel and second syringe barrel. The two components are initially separated by the rupturable membrane, which is irreversibly ruptured by applying sufficient pressure to the first plunger within the hollow syringe barrel prior to mixing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/525,961, filed to Aug. 5, 2009, which is a national phase ofInternational Application No. PCT/2007/067556, filed Apr. 26, 2007,which claims the benefit of U.S. patent application Ser. No. 11/673,334,filed Feb. 9, 2007. The disclosures of the foregoing are incorporatedherein in their entirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present application is directed to devices and methods for mixing,storing and dispensing two-part dental compositions.

2. The Relevant Technology

Many chemical formulations are packaged in two initially separate parts,often known as A and B components. Separate storage of the A and Bcomponents is often necessary where the composition resulting frommixing is unstable over time. For example, a self-etching dental primercomposition may be provided in two initially separate parts to preventthe acid component from slowly destabilizing the polymerizable resincomponent by hydrolyzing off the functional group(s) to which thebackbone of the resin is chemically bonded. Although suchdestabilization may not occur immediately upon mixing, with many suchcompositions, it is often recommended that the composition be used up ordiscarded within a certain time period (e.g., 30, 60, or 90 days) afterinitial mixing.

Because such compositions are unstable once mixed, it is important toensure that the two parts remain separated prior to mixing, so as toprevent premature mixing and destabilization. In addition, it is awkwardand time consuming for the practitioner to have to measure eachcomponent from a larger container, and then mix them together prior tointroducing the mixed composition into a storage and/or dispensingdevice. In light of the above, it would be an advantage to provide asyringe-in-syringe all in one mixing and dispensing system for use witha two-part composition that would provide a practitioner withpre-measured amounts of each component ready for mixing, and that wouldprovide the user with an all in one device that could easily beactivated to effect mixing, while also being used to store and laterdispense the composition. It would be a further advantage if theall-in-one mixing and dispensing device reduced the possibility ofpremature mixing of the components, while also being inexpensive andeasy to mass manufacture so as to be disposable to after a single use.

BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS

The present invention is directed to a hollow inner plunger for usewithin a syringe-in-syringe mixing system for mixing a two-part dentalcomposition. The hollow inner plunger includes a body having acontinuous cylindrical wall defining an internal chamber for containinga first component. The body includes a proximal end and a distal end. Asealing plug and rupturable membrane are disposed at the distal end ofthe body, and the sealing plug and rupturable membrane are integrallyformed together as a single piece (e.g., formed of a single piece ofelastomeric material).

Providing a sealing plug and rupturable membrane that are integral so asto comprise a single piece of material greatly simplifies the massmanufacture of the hollow inner plunger and a syringe-in-syringe mixingsystem of which it forms a part. The integral sealing plug andrupturable membrane provide a simple, low-cost way to ensure initialseparation of the two-parts of a two-part dental composition within thesyringe-in-syringe mixing system, while also minimizing and/orpreventing contamination that may otherwise occur if the rupturablemembrane were to comprise a separate part bonded to the distal end ofthe hollow inner plunger.

For example, any bonding adhesive used to bond a membrane may becontaminated or chemically attacked by one or both of the componentsseparated by the rupturable membrane causing weakening or failure of thebond (e.g., during storage). Furthermore, where the composition isintroduced into the chamber prior to bonding of the rupturable membrane,the composition may contaminate the wall or other surface to which themembrane is to be bonded, which may inhibit formation of a strong bond.In addition, any bonding adhesive may likewise contaminate or chemicallyreact with one or both of the two components to be separated, which mayrender the mixed composition less effective or otherwise unsuitable foruse. Therefore, providing an integral sealing plug and rupturablemembrane not only reduces the number of parts and steps required inassembly, but also reduces the likelihood of contamination of thetwo-part composition or any bonding adhesive.

The hollow inner plunger may comprise part of an associatedsyringe-in-syringe mixing system for use in mixing and dispensing atwo-part dental to composition. Such a system includes a first plunger,the hollow inner plunger as described above, and a syringe barrelconfigured to contain a second component. When assembled, the firstplunger is slidably disposed in sealing engagement within the hollowinner plunger, and the hollow inner plunger is slidably disposed insealing engagement within the syringe barrel. The first component isinitially stored within the chamber of the inner hollow plunger separatefrom the second component which is stored within the chamber of thesyringe barrel. The two chambers are initially separated by therupturable membrane.

In one embodiment, the internal chamber of the hollow inner plunger hasa diameter at the distal end of the body that is less than a diameter ofthe chamber at the proximal end. Preferably, this narrowing of diameteroccurs near the distal end of the body (e.g., adjacent to or near aproximal end of the integral sealing plug/rupturable membrane).Narrowing the diameter of the chamber significantly increases thepressure exerted by the first component against the rupturable membrane,which has been found to greatly aid in causing rupture of the membranein such a way that results in jetting of the first component into thesecond component. The result of such jetting action is nearinstantaneous mixing of the two components, particularly for tworelatively low viscosity liquids. As such, the internal diameter at thedistal end is preferably not more than about 75% of the largest diameterof the chamber (e.g., the diameter at the proximal end), more preferablynot more than about 50% of the largest diameter of the chamber (e.g.,the diameter at the proximal end), and most preferably not more thanabout 35% of the largest diameter (e.g., the diameter at the proximalend). The inventors have found that a diameter at the distal end (i.e.,adjacent the rupturable membrane) measuring about one-third that of thelargest diameter of the chamber (e.g., the diameter from the proximalend to a location adjacent the sealing plug where the diameter isabruptly narrowed) results in catastrophic rupture of the membrane andjetting of substantially all of the first component through therupturable membrane and into the second component to effect homogeneousmixing.

The actual thickness of the rupturable membrane depends on the strengthand other physical properties of the selected material, along with theconfiguration of any reduction in diameter leading up to the proximalend of the body where the membrane to is located. The rupturablemembrane preferably has a thickness ranging from about 0.0005 inch toabout 0.04 inch, more preferably from about 0.002 inch to about 0.025inch, and most preferably from about 0.005 inch to about 0.015 inch. Forexample, it has been found that a thermoplastic elastomer materialhaving a thickness from about 0.005 inch to about 0.010 inch isparticularly preferred for the reasons described above when the diameterof the internal chamber is reduced adjacent the distal end to aboutone-third of its value at the proximal end.

These and other advantages and features of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above recited and other benefits,advantages and features of the invention are obtained, a more particulardescription of the invention briefly described above will be rendered byreference to specific embodiments thereof which are illustrated in theappended drawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be consideredlimiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1A is a perspective view of an exemplary hollow inner plungerincluding an integrally formed sealing plug and rupturable membrane;

FIG. 1B is a close up cross-sectional view of a distal end of the hollowinner plunger including the integral sealing plug and rupturablemembrane of FIG. 1A;

FIG. 1C is a close up cross-sectional view of an alternative hollowinner plunger including an internal chamber of substantially constantdiameter along its entire length;

FIG. 2 is a perspective view of an exemplary syringe-in-syringe mixingsystem incorporating a hollow inner plunger according to the presentinvention;

FIG. 3A is a perspective view of an exemplary first plunger for use in asyringe-in-syringe mixing system, the first plunger including anexemplary locking mechanism to prevent pull-out of the first plungeronce it has been fully inserted within the hollow inner plunger;

FIG. 3B is a perspective view of an alternative first plunger includingan alternative locking mechanism;

FIGS. 3C-3D illustrate an alternative embodiment in which the integralsealing plug and rupturable membrane may be incorporated within asyringe-to-syringe mixing system;

FIG. 4A illustrates the first plunger being pressed into the hollowinner plunger so as to cause the rupturable membrane at the distal endof the hollow inner plunger to break, resulting in jet mixing of thefirst component into the second component;

FIG. 4B illustrates the first plunger in a locked configuration relativeto the hollow inner plunger so as to prevent pull-out of the firstplunger from the hollow inner plunger; and

FIG. 4C illustrates dispensing of a portion of the mixed two-partcomposition onto a pad for subsequent application to a desired surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Introduction

In one aspect, the present invention is directed to a hollow innerplunger for use within a syringe-in-syringe mixing system for mixing atwo-part dental composition. The hollow inner plunger includes a bodyhaving a continuous cylindrical wall defining an internal chamber forcontaining a first component. The body includes a proximal end and adistal end. A sealing plug and rupturable membrane are disposed at thedistal end of the body, and the sealing plug and rupturable membrane areintegrally formed together as a single piece (e.g., formed of a singlepiece of elastomeric material).

The hollow inner plunger may comprise part of an associatedsyringe-in-syringe mixing system for use in mixing and dispensing atwo-part dental composition. Such a system includes a first plunger, thehollow inner plunger as described above, and a syringe barrel configuredto contain a second component. When assembled, the first plunger isslidably disposed in sealing engagement within the hollow inner plunger,and the hollow inner plunger is slidably disposed in sealing engagementwithin the syringe barrel. The first component is initially storedwithin to the chamber of the inner hollow plunger separate from thesecond component which is stored within the chamber of the syringebarrel. The two chambers are initially separated by the rupturablemembrane.

II. Exemplary Hollow Inner Plungers

FIG. 1A is a perspective view of hollow inner plunger 100 having a bodyincluding a continuous cylindrical wall 102. The body and wall 102include a proximal end 104 and an opposite distal end 106. The interiorof wall 102 defines an internal chamber 108 configured to contain afirst component 110 a. A flange 112 is disposed at proximal end 104,while an integrally formed sealing plug and rupturable membrane 116 isdisposed at distal end 106. Advantageously, and as shown in FIG. 1B,sealing plug 114 and membrane 116 are integrally formed as a singlepiece, for example, from an elastomeric material. Rupturable membrane116 caps and seals off the distal end of hollow inner plunger 100 so asto contain first component 110 a within chamber 108, keeping it separatefrom a second component until the user desires to effect mixing. Sealingplug 114 is disposed on the outside of body wall 102 and is configuredto plug within a syringe barrel (see FIG. 2) so as to seal the proximalend of the syringe barrel when the hollow inner plunger 100 is assembledinto a syringe-in-syringe mixing system.

The distal portion of the body of hollow inner plunger 100 over whichsealing plug 114 is fitted advantageously includes an outwardlyextending annular ridge 118 that prevents plug 114 from being separatedfrom hollow inner plunger 100 during rupture of rupturable membrane 116.Sealing plug 114 includes a corresponding annular groove 120 configuredto matingly engage ridge 118 so as to securely attach sealing plug andrupturable membrane 116 to the body of hollow inner plunger 100.

Sealing plug 114 and rupturable membrane 116 may advantageously beformed of an elastomeric material (e.g., a thermoset elastomer orthermoplastic elastomer), which advantageously provides an excellentseal against a syringe barrel while also providing a desired strength torupturable membrane 116. Rupturable membrane 116 seals off the distalend of hollow inner plunger 100, separating first component 110 a from asecond component 110 b contained within a syringe barrel 128 (see FIG.2) until the user intentionally ruptures membrane 116, causing first tocomponent 110 a to be forced into syringe barrel 128, where the twocomponents are mixed together.

Providing a sealing plug 114 and rupturable membrane 116 that areintegral so as to comprise a single piece of material greatly simplifiesthe mass manufacture of the hollow inner plunger 100 and asyringe-in-syringe mixing system of which it forms a part. The integralsealing plug 114 and rupturable membrane 116 provide a simple, low-costway to ensure initial separation of the two-parts of a two-part dentalcomposition within a syringe-in-syringe mixing system, while alsominimizing and/or preventing contamination that may otherwise occur ifthe rupturable membrane 116 and sealing plug 114 were to comprise twoseparate parts requiring bonding of each to the body or wall 102.

For example, any bonding adhesive used to bond a rupturable membrane towall 102 (or any other structure) may be contaminated or chemicallyattacked by one or both of the components separated by the rupturablemembrane (e.g., during storage). Such contamination or chemical reactionwould likely lead to weakening and/or failure of the bond holding themembrane in place. Furthermore, where the composition is introduced intothe chamber prior to bonding of the rupturable membrane, the compositionmay contaminate the wall or other surface to which the membrane is to bebonded, which may inhibit formation of a good bond.

In addition, any bonding adhesive may likewise contaminate or chemicallyreact with one or both of the two components intended for separationwithin a syringe-in-syringe mixing system, which may render onecomponent, both components, or the mixed composition less effective orotherwise unsuitable for use. Therefore, providing an integral sealingplug and rupturable membrane not only reduces the number of parts andsteps required to assemble a hollow inner plunger and an associatedsyringe-in-syringe mixing system, but also reduces the likelihood ofcontamination of the two-part composition or any bonding adhesive,either of which could render the mixing system and/or compositionuseless.

FIGS. 1B and 1C illustrate cross-sectional views of alternativeembodiments. FIG. 1B illustrates an example in which the inside diameterof the chamber 108 is reduced adjacent to rupturable membrane 116, whileFIG. 1C illustrates an alternative example in which the diameter D ofthe chamber 108′ is not reduced, but is substantially constant along thelength of the chamber 108′ so that the diameter D adjacent membrane 116′and plug 114′ is substantially the same as the diameter D elsewherealong chamber 108′.

FIG. 1B shows a preferred embodiment in which the internal chamber 108of hollow inner plunger 100 has a diameter D_(S) at distal end 106 ofthe body that is less than a diameter D_(L) of the chamber at proximalend 104. As illustrated, preferably this narrowing of diameter occursnear the distal end 106 of the body. For example, in the illustratedembodiment, the narrowing of the chamber diameter occurs adjacent ornear the proximal edge of the sealing plug 114. Reducing the outsidediameter of the body wall 102 along this distal portion also providesspace for the receipt of sealing plug 114 in a way that presents anoverall outside diameter of the plunger 100 that is substantiallyconstant along the entire length (i.e., between proximal end 104adjacent flange 112 and distal end 106), with the exception of primaryand secondary sealing surfaces 122 a and 122 b, respectively, which areconfigured to seal against the inside surface of a syringe barrel. Suchan arrangement provides a tight fit of the inner plunger 100 within asyringe barrel (e.g., see FIG. 2), reducing any tendency of the innerplunger to wobble within the syringe barrel, which tendency may becomeparticularly pronounced further away from the sealing surfaces 122 a and122 b (e.g., near proximal end 104).

In addition, narrowing the diameter of chamber 108 significantlyincreases the pressure exerted by first component 110 a againstrupturable membrane 116, when force is selectively applied by a user toa plunger inserted within proximal end 104. Narrowing of diameter hasbeen found to greatly aid in causing rupture of membrane 116 in such away that results in jetting of first component 110 a into secondcomponent 110 b. The result of such jetting action is near instantaneousmixing of the two components, particularly for two relatively lowviscosity liquids.

As such, the internal diameter D_(S) at the distal end 106 is preferablynot more than about 75% of the diameter D_(L) at proximal end 104 andalong the remainder of chamber 108, more preferably not more than about50% of the diameter D_(L), and most preferably not more than about 35%of the diameter D_(L). The inventors have found that a diameter at thedistal end (i.e., adjacent the rupturable membrane) measuring aboutone-third that of the largest diameter of the chamber (e.g., thediameter is substantially constant from the proximal end 104 to alocation adjacent the sealing plug 114 where the diameter is abruptlynarrowed) results in catastrophic rupture of the membrane and jetting ofsubstantially all of the first component 110 a through the rupturablemembrane 116 and into the second component to effect homogeneous mixing.

The actual thickness of rupturable membrane 116 depends on the strengthand other physical properties of the selected material, along with theconfiguration of any reduction in diameter leading up to the proximalend of the body where the membrane is located. The rupturable membranepreferably has a thickness ranging from about 0.0005 inch to about 0.04inch, more preferably from about 0.002 inch to about 0.025 inch, andmost preferably from about 0.005 inch to about 0.015 inch. For example,it has been found that a rupturable membrane formed of a thermoplasticelastomer material having a thickness from about 0.005 inch to about0.010 inch is particularly preferred for the reasons described abovewhen the diameter D_(S) of the internal chamber 108 is reduced adjacentthe distal end 106 to about one-third of its value at the proximal end104.

III. Exemplary Syringe-in-Syringe and Syringe-to-Syringe Mixing Systems

FIG. 2 illustrates an exemplary syringe-in-syringe mixing system 124.System 124 includes a first plunger 126, a hollow inner plunger 100, anda syringe barrel 128 with a cap 130 at a distal end of syringe barrel128 (a plug fitting inside the distal end of barrel 128 couldequivalently be used). First plunger 126 is slidably disposed withinhollow inner plunger 100, which is slidably disposed within syringebarrel 128. As illustrated, hollow inner plunger 100 contains a firstcomponent 110 a, and syringe barrel 128 contains a second component 110b. First plunger 126 includes an elongate stem 132 and an associatedsealing plug 134 at a distal end of stem 132.

As perhaps best seen in FIG. 3A, a locking mechanism 136 mayadvantageously be included near a proximal end of first plunger 126 toprevent withdrawal of first plunger 126 from inner plunger 100 onceinserted. Such a locking mechanism is helpful as once the membrane isruptured, the device cannot be reused for mixing two components,although it can be used to dispense the mixed composition until all hasbeen dispensed. Locking first plunger within inner plunger 100 allowsthe dispensing device to operate as a syringe comprising a barrel andplunger, which simplifies dispensing by the user while also preventingslideout of the first plunger, which could result in loss, contaminationor waste of the mixed composition. Illustrated locking mechanism 136comprises a circumferentially extending portion of enlarged diameter 138(relative to the remainder of stem 132), with a plurality oflongitudinally extending interlock ribs 140. In use, interlock ribs 140are inserted into hollow inner plunger 100, where the ribs 140 biasagainst the inside wall 102 of hollow inner plunger 100. The system isconfigured such that when first plunger 126 is fully inserted intohollow inner plunger 100, circumferentially extending portion 138 restswithin flange 112 of hollow inner plunger 100, while interlock ribs 140extend distally into hollow inner plunger 100, past flange 112. Becauseflange 112 provides increased barrel strength relative to the remainderof hollow inner plunger 100, little or no deformation occurs to theinside wall of hollow inner plunger 100 on account of portion 138, butdeformation is caused by ribs 140, resulting in associated indentationsbeing formed into the inside wall 102 of hollow plunger 100 distal toflange 112, preventing, or at least inhibiting, later removal of firstplunger 126 from hollow inner plunger 100 (e.g., see FIG. 4D).

FIG. 3B illustrates an alternative first plunger 126′ including acylindrical elongate stem 132, and a sealing plug 134. The principledifference between the first plunger 126′ and first plunger 126 of FIG.3A and FIG. 2 is that first plunger 126′ includes an alternative lockingmechanism 136′ comprising an annular interlock ring 140′ rather than theenlarged diameter portion 138 and plurality of interlock ribs 140 of theembodiment of FIG. 3A. Similar to interlock ribs 140, annular interlockring 140′ causes the formation of an indentation or groove within theinside wall 102 of hollow inner plunger 100. Annular interlock ring 140′resides in the formed groove, preventing, or at least inhibiting, pullout of first plunger 126 once fully inserted into hollow inner plunger100. Other locking mechanisms (e.g., an interference fit of the firstplunger into the hollow inner plunger) may alternatively be used.

According to one method, a pre-measured, pre-filled syringe-in-syringemixing system (as shown in FIG. 2) may be manufactured by firstinserting first plunger 126 into hollow inner plunger 100 so that firstplunger 126 is slidably received within hollow inner plunger 100.Sealing plug 134 of first plunger 126 seals the proximal end of hollowinner plunger. First component 110 a may then be introduced intointernal chamber 108 of hollow inner plunger 100. Integrally formedrupturable membrane 116 and sealing plug 114 may then be placed overdistal end 106 of hollow inner plunger 100, effectively sealing firstcomponent 110 a within chamber 108. Next, hollow inner plunger 100 maybe inserted into syringe barrel 128 so that hollow inner plunger 100 isslidably received therein. Primary and secondary sealing surfaces 122 aand 122 b, respectively, form a seal to prevent passage of any fluidaround seal 114, while membrane 116 forms a seal to prevent passage ofany fluid through seal 114 until the membrane is intentionally rupturedby the user. Second component 110 b may then be introduced into syringebarrel 128 through the distal end of the barrel. Cap 130 may finally beplaced over the distal end of barrel 128 so as to seal the distal end.Assembly in such a manner prevents or at least minimizes the formationand entrapment of air bubbles within the chamber of the inner plunger100 and/or the syringe barrel 128, and is thus currently preferred.

FIGS. 3C-3D illustrate an alternative embodiment in which the integralsealing plug and rupturable membrane may be incorporated within asyringe-to-syringe mixing system 224. FIG. 3C illustrates across-sectional view of alternative syringe barrel 200 similar to thoseillustrated in FIGS. 1B-1C including a continuous cylindrical wall 202which defines an internal chamber 208 configured to contain a firstcomponent. The principal difference of alternative syringe barrel 200relative to those illustrated in FIGS. 1B and 1C is that syringe barrel200 is not configured to slide within a syringe barrel, but rather to becoupled to another syringe barrel so as to allow syringe-to-syringemixing (as opposed to syringe-in-syringe mixing), as shown in FIG. 3D.

Syringe barrel 200 includes means for coupling to another syringebarrel. In the illustrated embodiment, a female portion of a couplingmechanism is disposed at the distal end of barrel 200. A cylindricalouter wall 250 with grooves 252 formed therein acts to receive acorrespondingly shaped male portion of another syringe barrel, which isreceived within cylindrically extending cavity 254. The male portionincludes threads configured to engage within grooves 252. A male portionof a coupling mechanism may alternatively be disposed at the distal endof syringe barrel 200 which includes the integrally formed rupturablemembrane and sealing plug, with the female portion being disposed on theother syringe. Other coupling means and mechanisms will be apparent toone skilled in the art.

Similar to hollow inner plunger 100, syringe barrel 200 also includes arupturable membrane 216, a sealing plug 214, an outwardly extendingannular ridge 218, and annular groove 220. Rupturable membrane 216 capsand seals off the distal end of syringe barrel 200 so as to contain afirst component within chamber 208, keeping it separate from a secondcomponent until the user desires to effect mixing. Sealing plug 214 isdisposed on the outside of body wall 202, and although it does not slideor provide a seal against the inside of a syringe barrel (as in asyringe-in-syringe mixing system), its presence may help to seal andprevent any leaking that may otherwise occur between the two syringeswhen they are coupled together. In addition, such a sealing plug formedof an elastomeric material (e.g., a thermoplastic elastomer material)may improve the tightness, grip, and coupling strength of syringe barrel200 to another syringe barrel, as the male portion of the other syringebarrel contacts sealing plug 214 (i.e., plug 214 may increase couplingfriction by contacting or gripping the male portion of the coupledsyringe barrel). In addition, such an integral sealing plug andrupturable membrane, specifically the arrangement of annular ridge 218and annular groove 220, provides means for attaching rupturable membrane216 to syringe barrel 200 without the need for glue or any otheradhesive, which is helpful in preventing contamination as describedabove.

When it is desired to effect mixing of the two-part composition, theuser presses first plunger 226 into syringe barrel 200 so as to compressfirst component 110 a. Although it may be possible to first pressopposite plunger 226 a, this is less preferred as it may reduce thejetting mixing action of one component into the other. First plunger 226may include a mark label thereon indicating that it be pressed first(not shown). Once a sufficient force is applied, rupturable membrane 216breaks, causing first component 110 a to be expressed under pressurefrom syringe barrel 200 into syringe barrel 228 where it mixes withsecond component 110 b.

The force of such rupture and jetting of the first component 110 a intothe second component 110 b is often sufficient to effect homogeneousmixing, such that no additional mixing is required, although theillustrated syringe-to-syringe mixing system 224 easily allows a user toalternatingly press plungers 226 and 226 a so as to further mix the twocomponents together. Such a syringe-to-syringe mixing system may beparticularly preferred where one or both components are of particularlyhigh viscosity, such that additional mixing may be needed.

III. Exemplary Method of Use

FIG. 4A illustrates an exemplary syringe-in-syringe mixing system 124.When it is desired to effect mixing of the two-part composition, theuser may press first plunger 126 into hollow inner plunger 100 so as tocompress first component 110 a. Once a sufficient force is applied,rupturable membrane 116 breaks causing first component 110 a to beexpressed under pressure from hollow inner plunger 100 into syringebarrel 128 where it mixes with second component 110 b.

The force of such rupture and jetting of the first component 110 a intothe second component 110 b is sufficient to effect homogeneous mixing,such that no additional mixing (e.g., by shaking) is required,particularly where both components are low viscosity liquids. Althoughpreferred for use with liquid-liquid systems, first and secondcomponents 110 a and 110 b may each be a liquid, or one may be a solidpowder, as dictated by the characteristics of the two-part compositionto be mixed. The syringe-in-syringe mixer is particularly well suitedfor mixing together two relatively low viscosity liquids (e.g., lessthan about 100 centipoise, more preferably less than about 10centipoise, and most preferably less than about 3 centipoise), becauseof the ability of the system to cause one component to be forcefullyejected into the other component so as to effect mixing without anyadditional effort (e.g., shaking is not necessary). One contemplatedrelatively low viscosity liquid-liquid two-part composition is atwo-part self etching dental primer composition described in U.S. patentapplication Ser. No. 11/261,171, filed Oct. 28, 2005, and entitledSELF-ETCHING DENTAL PRIMER COMPOSITIONS AND METHODS AND SYSTEMSUTILIZING SUCH COMPOSITIONS.

Although particularly well suited for use with lower viscosity liquids,the system may also be used with higher viscosity liquids (e.g., up toabout 1000 centipoise or even up to about 3500 centipoise) or aliquid-solid powder two-part composition, although when used for mixingsuch two-part compositions further mixing beyond that provided by therupture of the membrane and turbulent jetting of one component into theother may be necessary. For example, it may be helpful when mixing sucha composition to remove cap 130 and couple the system to another syringeso as to allow syringe-to-syringe mixing of the composition.

In other words, the rupturable membrane 116 is configured to only passfirst component 110 a for mixing with second component 110 b under apressure sufficiently high to cause jetting of the first component intothe second component (e.g., so as to create turbulence sufficient to mixthe two components together). Cap 130 may include a check-valve or othervent (not shown) that permits air or other gas within barrel 128 to beexpelled as first component 110 a is expressed into barrel 128. Anycheck-valve known in the art can be used or modified to attach to barrel128.

The system may advantageously be configured such that a force requiredto rupture membrane 116 is approximately equal to a force required toinsert and lock locking mechanism 136 (i.e., enlarged diameter portion138 and interlocking ribs 140) of the cylindrical elongate stem 132 intohollow inner plunger 100, although it is not required. Such aconfiguration provides a smooth and continuous movement and feel duringuse of the system as first plunger 126 is pressed into hollow innerplunger 100, rupturing membrane 116 and locking first plunger 126 intohollow inner plunger 100, all within a single movement. FIG. 4Billustrates the system once first plunger 126 has been fully insertedinto hollow inner plunger 100. In this configuration, first plunger 126is locked into hollow inner plunger 100.

In the locked configuration as shown, it is difficult, if notimpossible, to withdraw first plunger 126 from hollow inner plunger 100without destroying the system. Enlarged diameter portion 138 is disposedwithin the center of flange 112, while ribs 140 extend distally fromflange 112 further into hollow inner plunger 100. Because flange 112 hasincreased barrel strength relative to the area of hollow inner plunger100 immediately distal to flange 112, the inside wall surface 102 ofhollow inner plunger will be deformed by ribs 140 so as to form adepression into the portion of the contacted inside wall 102. At thesame time, the inside wall surface 102 of hollow inner plunger 100directly under flange 112 will be deformed only slightly if at allbecause of the increased barrel strength of the flange region 112compared to the region contacted by ribs 140. In other words, ribs 140create an interlock with the inside surface of hollow inner plunger 100,preventing, or at least inhibiting, subsequent withdrawal of firstplunger 126 from hollow inner plunger 100.

FIG. 4C illustrates the system 124 with a dispensing tip 142 coupled ata distal end of barrel 128 so as to allow the user to dispense the mixedtwo-part composition 110. As illustrated, composition 110 maybedispensed onto a pad for subsequent application (e.g., with a brushtool). Alternatively composition 110 may be dispensed directly onto atooth or other surface, depending on the preference of the user.

It will be appreciated that the present claimed invention may beembodied in other specific forms without departing from its spirit oressential characteristics. The described embodiments are to beconsidered in all respects only as illustrative, not restrictive. Thescope of the invention is, therefore, indicated by the appended claimsrather than by the foregoing description. All changes that come withinthe meaning and range of equivalency of the claims are to be embracedwithin their scope.

What is claimed is:
 1. A hollow syringe barrel for use within a syringemixing system for mixing a two-part composition, the hollow syringebarrel comprising: a hollow body including a continuous cylindrical walldefining an internal chamber for containing a first component, thehollow body having a proximal end and a distal dispensing end; a singledispensing orifice at the distal dispensing end of the hollow bodythrough which a first component contained in the internal chamber can bedispensed; and a rupturable membrane disposed at the distal dispensingend of the hollow body and which caps and seals off the singledispensing orifice until irreversible rupture of the rupturable membraneby application of sufficient pressure on a first component contained inthe internal chamber so as to irreversibly rupture the rupturablemembrane, wherein the rupturable membrane has a cross-sectionalthickness that facilitates rupture of the rupturable membrane duringuse.
 2. A hollow syringe barrel as in claim 1, wherein the internalchamber has a diameter at the distal end of the body that is less than adiameter of the internal chamber at the proximal end of the body.
 3. Ahollow syringe barrel as in claim 2, wherein the internal chamber has adiameter at the distal end of the body that is not more than about 75%of a diameter of the chamber at the proximal end.
 4. A hollow syringebarrel as in claim 2, wherein the internal chamber has a diameter at thedistal end of the body that is not more than about 50% of a diameter ofthe chamber at the proximal end.
 5. A hollow syringe barrel as in claim2, wherein the internal chamber has a diameter at the distal end of thebody that is not more than about 35% of a diameter of the chamber at theproximal end.
 6. A hollow syringe barrel as in claim 1, wherein therupturable membrane comprises an elastomeric material.
 7. A hollowsyringe barrel as in claim 6, wherein the rupturable membrane comprisesa thermoplastic elastomer or a thermoset elastomer.
 8. A hollow syringebarrel as in claim 1, wherein the rupturable membrane has a thicknessbetween about 0.0005 inch and about 0.04 inch.
 9. A hollow syringebarrel as in claim 1, wherein the rupturable membrane has a thicknessbetween about 0.002 inch and about 0.025 inch
 10. A hollow syringebarrel as in claim 1, wherein the rupturable membrane has a thicknessbetween about 0.005 inch and about 0.015 inch.
 11. A hollow syringebarrel as in claim 1, further comprising a flange disposed at theproximal end of the body.
 12. A hollow syringe barrel as in claim 1,further comprising an outwardly extending annular ridge disposed nearthe distal end of the hollow body and a sealing plug attached to therupturable membrane and having a corresponding annular groove configuredto matingly engage the annular ridge so as to attach the sealing plugand rupturable membrane to the hollow body of the hollow syringe barrel.13. A hollow syringe barrel as in claim 1, further comprising couplingmeans disposed at the distal dispensing end of the body for coupling thesyringe barrel to another syringe barrel so as to facilitate forsyringe-to-syringe mixing.
 14. A hollow syringe barrel as in claim 13,wherein the coupling means comprises a female portion of a couplingmechanism, including a cylindrical outer wall with grooves formedtherein, configured to receive a correspondingly shaped male portion ofanother syringe barrel.
 15. A hollow syringe barrel as in claim 13,wherein the coupling means comprises a male portion of a couplingmechanism, including raised threads formed therein, configured to bereceived within a correspondingly shaped female portion of anothersyringe barrel.
 16. A syringe-to-syringe mixing system comprising: ahollow syringe barrel as recited in claim 1; and a second syringe barrelhaving a distal dispensing end that is couplable to the distaldispensing end of the hollow body of the hollow syringe barrel.
 17. Asyringe-to-syringe mixing system as in claim 16, further comprising: afirst component of a two-component composition initially containedwithin the internal chamber of the hollow body of the hollow syringebarrel; a first plunger slidably disposed within the hollow body of thehollow syringe barrel for applying pressure to the first componentwithin the internal chamber; a second component of the two-componentcomposition initially contained within a second internal chamber of thesecond syringe barrel; and a second plunger slidably disposed within thesecond syringe barrel for applying pressure to the second componentwithin the second internal chamber of the second syringe barrel.
 18. Asyringe-in-syringe mixing system comprising: a hollow syringe barrel asrecited in claim 1; a sealing plug disposed at the distal dispensing endof the hollow body and which cooperates with the rupturable membrane toform a sealing plug-rupturable membrane body; and a second syringebarrel having a second internal chamber configured to slidably receivethe hollow syringe barrel therein so that the sealing plug sealinglyengages an interior wall of the second syringe barrel defining thesecond internal chamber.
 19. A syringe-in-syringe mixing system as inclaim 18, further comprising: a first component of a two-componentcomposition initially contained within the internal chamber of thehollow body of the hollow syringe barrel; a plunger slidably disposedwithin the hollow body of the hollow syringe barrel for applyingpressure to the first component within the internal chamber; and asecond component of the two-component composition initially containedwithin the second internal chamber of the second syringe barrel, whereinthe hollow syringe barrel is slidably received within the secondinternal chamber of the second syringe barrel and acts as a secondplunger during use for applying pressure to a mixture of the firstcomponent and the second component after being mixed together.
 20. Amethod of manufacturing a hollow syringe barrel comprising: providing ahollow body including a continuous cylindrical wall defining an internalchamber for containing a first component, the hollow body having aproximal end and a distal end terminating with a single dispensingorifice through which a first component can be dispensed; providing arupturable membrane comprised of an elastomeric material and having across-sectional thickness to facilitate rupture of the rupturablemembrane during use; and placing the rupturable membrane over the singledispensing orifice at the distal dispensing end of the hollow body inorder for the rupturable membrane to cap and seal off the single orificeuntil irreversible rupture of the rupturable membrane by application ofsufficient pressure on a first component contained in the internalchamber so as to irreversibly rupture the rupturable membrane.
 21. Amethod as in claim 20, further comprising introducing a first componentinto the internal chamber of the hollow syringe barrel and inserting aplunger partially through the internal chamber prior to placing theintegrally formed sealing plug and rupturable membrane over the distaldispensing end of the body.
 22. A hollow syringe barrel for use within asyringe-to-syringe mixing system for mixing a two-part composition, thesyringe barrel comprising: a hollow body including a continuouscylindrical wall defining an internal chamber for containing a firstcomponent, the body having a proximal end and a distal dispensing endterminating with a single dispensing orifice through which a firstcomponent in the internal chamber can be dispensed; a rupturablemembrane disposed at the distal dispensing end of the body so as to capand seal off the single orifice until irreversible rupture of therupturable membrane by application of sufficient pressure on a firstcomponent contained in the internal chamber so as to irreversiblyrupture the rupturable membrane, wherein the rupturable membrane has across-sectional thickness to facilitate rupture of the rupturablemembrane during use; and coupling means disposed at the distaldispensing end of the hollow body for coupling the syringe barrel toanother syringe barrel so as to allow for syringe-to-syringe mixing. 23.A hollow syringe barrel as in claim 22, wherein the coupling meanscomprises a female portion of a coupling mechanism, including acylindrical outer wall with grooves formed therein, configured toreceive a correspondingly shaped male portion of another syringe barrel.24. A hollow syringe barrel as in claim 22, wherein the coupling meanscomprises a male portion of a coupling mechanism, including raisedthreads formed therein, configured to be received within acorrespondingly shaped female portion of another syringe barrel.
 25. Ahollow syringe barrel as in claim 22, wherein the internal chamber has adiameter at the distal end of the body that is less than a diameter ofthe internal chamber at the proximal end of the body.
 26. A hollowsyringe barrel as in claim 22, wherein the rupturable membrane comprisesan elastomeric material and has a thickness between about 0.0005 inchand about 0.04 inch.
 27. A hollow syringe barrel as recited in claim 22,further comprising an outwardly extending annular ridge disposed nearthe distal dispensing end of the hollow body and a sealing plug attachedto the rupturable membrane and having a corresponding annular grooveconfigured to matingly engage the annular ridge so as to attach thesealing plug and rupturable membrane to the hollow body of the hollowsyringe barrel.
 28. A syringe-to-syringe mixing system comprising: ahollow syringe barrel as recited in claim 22; and a second syringebarrel having a distal dispensing end that is couplable by the couplingmeans to the distal dispensing end of the hollow body of the hollowsyringe barrel.
 29. A syringe-to-syringe mixing system as in claim 28,further comprising: a first component of a two-component compositioninitially contained within the internal chamber of the hollow body ofthe hollow syringe barrel; a first plunger slidably disposed within thehollow body of the hollow syringe barrel for applying pressure to thefirst component within the internal chamber; a second component of thetwo-component composition initially contained within a second internalchamber of the second syringe barrel; and a second plunger slidablydisposed within the second syringe barrel for applying pressure to thesecond component within the second internal chamber of the secondsyringe barrel.
 30. A syringe-in-syringe mixing system for use in mixinga two-part dental composition comprising: a first plunger; a hollowinner plunger configured to slidably receive the first plunger thereinin sealing engagement, the hollow inner plunger comprising: a hollowbody including a continuous cylindrical wall defining a first internalchamber for containing a first component, the hollow body having aproximal end and a distal end terminating with a single dispensingorifice through which a first component can be dispensed; a sealing plughaving at least one outwardly protruding circumferential sealing ridgefor sealing against an inner wall of a hollow syringe barrel; and arupturable membrane attached to the sealing plug and capping and sealingoff the single orifice until irreversible rupture of the rupturablemembrane by application of sufficient pressure on a first componentcontained in the first internal chamber so as to irreversibly rupturethe rupturable membrane; and the hollow syringe barrel including aninner wall and a second internal chamber configured to contain therein asecond component, the hollow syringe barrel being configured to slidablyreceive the hollow inner plunger therein in sealing engagement with theat least one circumferential sealing ridge of the sealing plug sealingagainst the inner wall of the syringe barrel defining the secondinternal chamber.
 31. A syringe-to-syringe mixing system as in claim 30,further comprising: a first component of a two-component compositioninitially contained within the first internal chamber of the hollow bodyof the hollow inner plunger; and a second component of the two-componentcomposition initially contained within the second internal chamber ofthe hollow syringe barrel.